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The power transfer of a dual active bridge (DAB) dc–dc converter is not linearly proportional to the phase shift between the two active bridges. When the DAB converter controller receives the power reference, the phase shift needs to be obtained by either solving a quadratic equation online or looking up from a table. The online calculation method is computationally inefficient. The lookup table method has only limited operating points. In addition, when using interpolation to find missing operating points from the table, the control accuracy will be reduced. This letter proposes a simple phase-shift modulation using a parabolic carrier. The proposed method converts the power command into phase shift by modulation. Therefore, the solving of the quadratic equation can be eliminated. The Verilog results are provided to verify the proposed parabolic carrier. A case study of DAB with sinusoidal ripple current charging concept is provided to demonstrate the advantage of the proposed method. [ABSTRACT FROM AUTHOR]

Despite the fact that in recent years, vision-based tracking approaches have made significant progress, the task of tracking vehicles at night still remains challenging. Visual information is strongly deteriorated or at least degraded due to poor illumination conditions. This reduces the perceptive ability of vision systems significantly and can even lead to target loss, resulting in false estimation and/or false prediction of object behavior. In this paper, we propose a novel online-learning method to track vehicles at night. Our method is based on the kernelized correlation filter and assembles different feature channels to kernelized experts. By estimating their reliabilities, we force the appearance model to focus on the most discriminative visual features to accomplish the classification. In addition, a temporal optimization step in conjunction with a memory model is used to remove outliers and keep the most reliable samples to train the tracker models. Experiments over various daytime and weather conditions show that our approach outperforms existing trackers at night and in case of bad weather while offering state-of-the-art performance in more favorable situations. As our tracker has only little computational cost, it is appropriate for use cases with real-time requirements like in automotive or industrial applications. [ABSTRACT FROM AUTHOR]

Real-time junction temperature measurements can be very beneficial for improving power converter's design, performance, and reliability. Junction temperature sensing using an on-die diode sensor is a promising solution. However, a strong low-pass filter is usually applied to filter out the sensor's noise during switching transients, which reduces the sensor's bandwidth. This paper aims to improve the sensing system's bandwidth to achieve an ultrafast real-time junction temperature measurement. Three noise coupling mechanisms have been identified and verified by both simulations and experiments. The noise coupling model-based crosstalk capacitances estimation method is proposed and validated. Noise mitigation methods are proposed, thus only a 200-kHz low-pass filter is needed for the noise suppression purpose, which is a significant improvement from the current field implementation of tens of hertz bandwidth. [ABSTRACT FROM AUTHOR]

The physical characteristics of gallium nitride (GaN) make it theoretically superior to silicon (Si) in such aspects as the temperature of operation, switching speed, breakdown voltage, and efficiency. While much research has been conducted on GaN devices, the discussion of third-quadrant operation is limited. Furthermore, the merits of GaN transistors, particularly their fast switching speed and low on-resistance, make them suitable for switched-capacitor circuits. This paper demonstrates the ability of a GaN transistor to function as a synchronous rectifier in a switched-capacitor circuit. A 500 W GaN-based voltage doubler capable of achieving zero-current switching is presented with supporting experimental results. This circuit achieves peak efficiencies of 97.6% and 96.6% while switching at frequencies of 382 and 893 kHz, respectively. [ABSTRACT FROM PUBLISHER]

In this paper, several modular converter topologies based on a switched-capacitor-cell concept are introduced for high-power applications. Two types of switched-capacitor cells, including the full cell and the half-cell, are discussed. The full cell can be used for dc–ac inversion, and the half-cell is utilized in both dc–dc and dc–ac applications. A rotational charging scheme is adopted for the half-cell-based dc–dc voltage multiplier to eliminate the large output capacitor that exists in many traditional switched-capacitor topologies. A soft-switching scheme, which does not require extra components, is adopted to reduce the switching loss and electromagnetic interference. A variable switching frequency control scheme is proposed to realize soft switching for dc–ac inverters. The experimental results on a 2-kW prototype are presented to verify the proposed topologies. [ABSTRACT FROM PUBLISHER]

In medium-/high-power inverters, optimal pulse-width modulation (OPWM) is often used to reduce the switching frequency and at the same time, realize selective harmonic elimination (SHE). For both two-level and multilevel inverters, most selective harmonic elimination (SHE) studies are based on solving multiple variable high-order nonlinear equations. Furthermore, for multilevel inverters, SHE has been often studied based on the assumption of balanced dc levels and single switching per level. In this paper, the authors further developed harmonics injection and equal area criteria-based four-equation method to realize OPWM for two-level inverters and multilevel inverters with unbalanced dc sources. For the cases, where only small number of voltage levels are available, weight oriented junction point distribution is utilized to enhance the performance of the four-equation method. A case study of multilevel inverter at low-modulation index is used as an example. Compared with existing methods, the proposed method does not involve complex equation groups and is much easier to be utilized in the case of large number of switching angles, or multiple switching angles per voltage level in multilevel inverters. [ABSTRACT FROM AUTHOR]